Fluid couplings for pressurized fluid systems commonly employ interconnectable self-sealing male and female parts. In the most common arrangement the female part includes a cylindrical passage which receives the cylindrical nose of the male part. An annular seal located within a gland recess in one of the parts sealingly engages the other part to establish a fluid-tight relationship between the coupling parts, and locking means defined upon the parts maintain the parts in coupled relationship during use.
Self-sealing valves within the coupling parts automatically seal during disconnection of the parts, and automatically open as the parts are interconnected. A typical example of this type of fluid coupling is represented by the Series FD49 coupling manufactured by the assignee, Aeroquip Corporation of Jackson, Michigan.
In some pressurized fluid systems relatively high pressures are employed, i.e. over 1000 psi, and frequent connection and disconnection of the coupling parts occurs, such as in the use of hydraulically operated tools. During the connection and disconnection of the coupling parts, the annular seal between the parts is exposed to the pressurized fluid prior to the seal being completely internally supported. This exposure of the unsupported seal to high pressure hydraulic fluid often causes the seal to "blow-out" from its recess due to distortion of the seal by the pressurized fluid. Of course, such a "blow-out" destroys the sealing ability of the coupling, and a new seal must be installed to restore the coupling to a usable state.
It is an object of the invention to provide a seal for use with a coupling for pressurized fluid systems wherein the seal resists "blow-out", when the coupling parts are connected under pressure and overcomes many of the problems previously attendant with seals used in a similar environment and coupling type.
A further object of the invention is to provide a seal for pressurized fluid systems which may be installed within a standard annular gland recess and includes a body of synthetic plastic material having sufficient mass and internal strength to resist deformation and also provide support for an elastomeric O-ring mounted upon the outer portion of the body.
In the practice of the invention a two-part seal is utilized which is most commonly located within the male part of a two-part fluid coupling. The seal is located within an annular gland recess of standard dimension intersecting the male part passage, and the seal engages the cylindrical surface of a valve component of the female part when the male part is inserted into the female part passage.
The seal includes a primary annular body formed of synthetic plastic material, preferably polytetrafluoroethylene, having an inner cylnidrical bore for sealingly engaging the cylindrical poppet valve of the male part with an interference fit. The outer circumference of the seal body is circular, and a recess is defined in the outer circumference concentric with the seal axis and centrally located between the radially extending body sides defining the seal body length.
An elastomeric O-ring is located within the seal body recess, and the O-ring has a cross-sectional diameter greater than the radial depth of the recess so as to extend radially beyond the seal body circumference. The O-ring seals the primary body with respect to the male part gland recess.
In accord with the concepts of the invention the dimensions of the primary seal body are the maximum to fit the seal into a standard gland recess to resist deformation due to fluid pressure and prevent "blow-out". To this end the cross-sectional radial thickness of the primary seal body is only slightly less than the gland recess radial depth and the cross-sectional radial thickness of the primary body from its inner diameter to the bottom surface of the O-ring receiving recess is, preferably, at least equal to the radial depth of the recess. Further, the axial dimension of the primary seal body is only slightly less than the gland recess axial length and the axial dimension of the seal body on each axial side of the O-ring receiving recess is sufficient to properly support the O-ring against extrusion around the body circumference, and preferably, the axial thickness between the radial side of the seal body and the nearest recess side is approximately equal to the radial thickness of the body between its inner diameter and bottom surface of the O-ring receiving recess.
While the primary seal body is semi-rigid, it is capable of sufficient manual deformation to permit installation in the coupling part gland recess, and it is one of the features of a seal in accord with the inventive concept that it may be readily assembled to its associated coupling part and retrofitted into a standard gland recess without modification to the coupling part or gland.